In a mixing bowl, mix the water and flour from the "ingredients" stage, then sprinkle the yeast and sugar on top, stir a bit (the water should be about 110 degrees to make a good environment for the yeast.) then let stand for 15-30 minutes (or until the yeast mixture make bubbles and raising in volume)
Stir in the remaining milk, flour, salt, sugar, and oil. Mix well into dough. Lightly flour your work surface, turn the dough onto it, and knead it until it's smooth. Then grease another bowl lightly with oil, return the kneaded dough to the bowl, roll it around to coat the ball with grease, cover it, and let it stand for 30 minutes to 1 hour (or until dough doubled in size)
Punch down the dough with the back of your fist, then spread it on the lightly floured working surface. Sprinkle the baking powder evenly over it and then knead it for five minutes. Then put half of the dough back in the bowl and cover it again, and pull off bits of the dough you still have out and shape them into spheres. Fill the middle of the dough with red bean paste. Pinch to seal.
Place buns (seam down) on squares of waxed paper. Then cover the filled buns and let them rise for another half hour.
Bring water to a boil then reduce the heat to a simmer. Place the vegetable steamer then place some buns (still on their waxed paper) leaving an inch between them.
Put a clean dry napkin over the top, and put the lid on over that. (This will prevent condensation from dripping back down on the buns and creating blisters.)
Steam them over simmering water for about 15 minutes. Repeat until all buns steamed well and firm. Serve warm or at room temperature. Enjoy :)